Despite the favorable prognosis of stage IA non-small cell lung cancer (NSCLC), the disease recurs after complete surgical resection in 20%-30% of patients. This study determined the prognostic value of various metabolic parameters of 18 F-FDG PET/CT in surgically resected stage IA NSCLC. Methods: We retrospectively reviewed 248 patients with stage IA NSCLC who underwent lobectomy and complete lymph node dissection after PET/CT. A region of interest was drawn on the primary lesion, and metabolic indices such as metabolic tumor volume, maximum standardized uptake value (SUV max ), and total lesion glycolysis (TLG) were measured using an SUV cutoff of 2.5. Results: The patients included 134 men and 114 women, and the mean age was 63.03 ± 10.01 y; 129 were stage T1a (#2 cm) and 119 were T1b (.2 cm). The median follow-up period was 36.6 mo. Recurrence took place in 15 patients. The mean (±SD) SUV max , metabolic tumor volume, and TLG were 4.55 ± 3.75, 5.92 ± 5.57, and 14.42 ± 17.35, respectively. The cutoffs of SUV max and TLG were 3.7 and 13.76, respectively. The 5-y overall survival (OS) was 95.1% in low-SUV max patients and 82.2% in high-SUV max patients (P 5 0.02). The 5-y OS was 93.7% in low-TLG patients and 78.3% in high-TLG patients (P 5 0.01). On multivariate analysis, TLG was a risk factor for OS (hazard ratio, 3.159; P 5 0.040), but SUV max showed marginal significance (P 5 0.064). The concordance index of the TLG model was 0.676 (95% CI, 0.541-0.812). Conclusion: TLG was a significant prognostic factor for OS in patients with stage IA NSCLC. Lungcanceri s the second most common cancer in both men and women and the most common cause of cancer death in the world (1). Non-small cell lung cancer (NSCLC) accounts for 80%-85% of all lung cancer cases. Oncologic treatment options for NSCLC typically include surgery, radiation, and chemotherapy, either alone or in combination. TNM stage has been considered the primary prognostic factor in NSCLC. However, tumor-and patientspecific factors vary even within the same disease stage, creating a heterogeneous population of patients, each with an individual prognosis that requires consideration of patient-and tumor-specific factors for best estimation (2,3). Recently, the incidence of earlystage NSCLC has increased as a result of the use of low-dose CT for screening. However, despite having early-stage disease, up to 20%-30% of patients with stage IA NSCLC relapse after surgical treatment. Therefore, other prognostic factors besides TNM stages are needed to identify patients at high risk for recurrence, predict prognosis, and recommend individualized adjuvant therapy (4).18 F-FDG PET relies on the fact that most neoplasms are highly metabolically active and therefore can be detected on a background of relatively less active normal tissues. When performed in addition to qualitative evaluation by visual inspection, 18 F-FDG PET can provide several semiquantitative measurements of radioactivity concentration in each tissue compartment, such as standardized uptake value (SUV...